Journal of Medical and Biological Engineering, 33(2): 207-214 207 Bioactivity and Biocompatibility Studies on Silk-Based Scaffold for Bone Tissue Engineering Sahba Mobini 1,2 Mehran Solati-Hashjin 2,3,* Habibollah Peirovi 4 Noor Azuan Abu Osman 3 Mazaher Gholipourmalekabadi 5 Mahmoud Barati 6 Ali Samadikuchaksaraei 7 1 Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran 19615, Iran 2 Nanobiomaterials Laboratory, Biomaterials Center of Excellence, Amirkabir University of Technology, Tehran 15914, Iran 3 Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia 4 Nanomedicine and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran 4739, Iran 5 Department of Biotechnology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran 4739, Iran 6 Department of Pharmaceutical Biotechnology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran 4739, Iran 7 Department of Biotechnology and Cellular and Molecular Research Center, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran 141761, Iran Received 13 Nov 2011; Accepted 27 Jul 2012; doi: 10.5405/jmbe.1065 Abstract Novel materials with promising properties can be used to achieve scaffold-based tissue engineering goals. Natural silk (NS) polymer has remarkable biomedical and mechanical properties as a material for bone tissue engineering scaffolds. This study describes the fabrication of a silk-based composite, in which natural silk and regenerated silk (RS) are combined to achieve better mechanical properties in the three-dimensional (3D) porous form. The biocompatibility and bioactivity of these scaffolds are evaluated. RS was made using mulberry-silk cocoons. RS/NS composite scaffolds were fabricated using the freeze-drying technique. Silk protein extract was evaluated by Fourier transform infrared spectroscopy (FTIR), with sharp amide peaks appearing at 1655 cm -1 and 1530 cm -1 in the FTIR spectrum, confirming the existence of fibroin. The fabricated 3D scaffolds were morphologically analyzed by scanning electron microscopy (SEM). An inter-connective spongy structure was found. Mechanical characterizations were carried out using a universal testing machine. Results show that the mechanical properties of the RS/NS composites are better than those of scaffolds fabricated with RS alone. In addition, in vitro tests, including those for cell viability and adhesion, were carried out with osteoblast cells by the MTT assay with a new calculation approach, which confirmed biocompatibility. The bioactivity potential of the RS and composites fibers was tested by introducing scaffolds to normal simulated body fluid for 21 days. Energy-dispersive X-ray spectroscopy and SEM analyses proved the existence of CaP crystals for both configurations. Thus, reinforced silk composite is a bioactive and biocompatible alternative for bone tissue engineering applications. Keywords: Bone tissue engineering, Biocompatible materials, Scaffold, Silk 1. Introduction Bone is a complex and highly specialized connective tissue [1,2]. As the provision of structural support for the body is bone’s main role, any structural bone defect that leads to functional deficits can dramatically affect an individual’s well- being and quality of life [3]. Tissue engineering can provide an alternative to traditional treatment protocols by replacing living * Corresponding author: Mehran Solati-Hashjin Tel: +98-21-64542360; Fax: +98-21-66468186 E-mail: solati@aut.ac.ir tissue with tissue grown in vitro to meet each patient’s individual needs [4,5]. Various materials and scaffold fabrication techniques have been investigated over the past two decades for bone tissue engineering with the aim to increase mechanical stability and improve scaffold-tissue interactions [6]. Requirements for mechanical properties, biocompatibility, and bioactivity must be met to ensure scaffold utility, particularly for bone tissue regeneration [7,8]. Silks are natural fibers produced by various insects, of which mulberry silkworms (Bombyx mori (B. mori)) are of high economic importance, as they can be reared in captivity [9,10]. Recently, it has been shown that silks can be employed for a variety of